Please be advised that importing Bitcoin addresses is only available in the web wallet.
1) Log into your wallet via web-browser.
2) Navigate to Settings - Wallets & Addresses
3) Select Bitcoin and click Import Address button on the right
4) Enter the private key, label (name) and choose the wallet to which you'd like to transfer funds to (optional)
5) Click Import Private Key button and that's it, the address will appear under the Imported Bitcoin Addresses section and will become available for sending and receiving.
Please note that private key format must be compressed WIF. If you are importing a private key that is in an uncompressed format, please convert it to compressed prior to importing.
If you have any further questions or need assistance, please contact our support team.